Display apparatus having zero bezel by bending bezel area

ABSTRACT

Currently described is a display that has a base layer, and on top of that base layer is a buffer layer with two exposed portions. The exposed portions are covered with a film. A pixel layer is placed between the two films, and a first substrate is attached to the pixel layer using an adhesive layer. The substrate is designed using either multiple thicknesses or grooves to facilitate a curvature radius of the end portions of the display to achieve a zero bezel display.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of the Korean Patent Application No.10-2017-0143918 filed on Oct. 31, 2017, which is hereby incorporated byreference for all purposes as if fully set forth herein.

FIELD OF THE DISCLOSURE

The present disclosure relates to a display apparatus.

BACKGROUND

With the advancement of the information age, a demand for a displaydevice for displaying an image has been increased in various forms.Recently, a display device of a slimmer size has been launched.Particularly, a flexible display device has many advantages includingthat it is easy to carry and have various shaped devices.

Since the flexible display device includes a bending area that may folda substrate and may reduce a bezel size by folding the substrate at thebending area, the flexible display device may be realized as a displaydevice having a narrow bezel.

However, as a bending level is increased to have a narrower bezel, thestress on the edges of the panel is increased and a stress inside apanel becomes strong, causing problems to occur, for example, a lightemitting diode layer is laminated and a thin film transistor is shorted.

SUMMARY

Accordingly, the present disclosure is directed to a display apparatusthat substantially obviates one or more problems due to limitations anddisadvantages of the related art.

An advantage of the present disclosure is to provide a display apparatusthat may have a zero bezel by facilitating bending.

Additional advantages and features of the disclosure will be set forthin part in the description which follows and in part will becomeapparent to those having ordinary skill in the art upon examination ofthe following or may be learned from practice of the disclosure. Theobjectives and other advantages of the disclosure may be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the disclosure, as embodied and broadly described herein,there is provided a display apparatus comprising a first substratehaving a display area and a non-display area surrounding the displayarea; a pixel array layer provided on the display area of the firstsubstrate; and a second substrate provided on the pixel array layer,having a first area and a second area bent from the first area, whereinthe second substrate has thicknesses different in the first area and thesecond area.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 is a plane view illustrating the state that a display apparatusaccording to one embodiment of the present disclosure is not bent;

FIG. 2 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the first embodiment ofthe present disclosure;

FIG. 3 is a cross-sectional view illustrating a bent state of a displayapparatus shown in FIG. 2;

FIG. 4 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the second embodiment ofthe present disclosure;

FIG. 5 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the third embodiment ofthe present disclosure;

FIG. 6 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the fourth embodiment ofthe present disclosure;

FIG. 7 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the fifth embodiment ofthe present disclosure;

FIG. 8 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the sixth embodiment ofthe present disclosure; and

FIG. 9 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the seventh embodiment ofthe present disclosure.

DETAILED DESCRIPTION

Advantages and features of the present disclosure, and implementationmethods thereof will be clarified through following embodimentsdescribed with reference to the accompanying drawings. The presentdisclosure may, however, be embodied in different forms and should notbe construed as limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the present disclosureto those skilled in the art. Further, the present disclosure is onlydefined by scopes of claims.

A shape, a size, a ratio, an angle, and a number disclosed in thedrawings for describing embodiments of the present disclosure are merelyexamples, and thus, the present disclosure is not limited to theillustrated details. Like reference numerals refer to like elementsthroughout the specification. In the following description, when thedetailed description of the relevant known function or configuration isdetermined to unnecessarily obscure the important point of the presentdisclosure, the detailed description will be omitted.

In a case where ‘comprise’, ‘have’, and ‘include’ described in thepresent specification are used, another part may be added unless ‘only˜’is used. The terms of a singular form may include plural forms unlessreferred to the contrary.

In construing an element, the element is construed as including an errorrange although there is no explicit description.

In describing a position relationship, for example, when the positionrelationship is described as ‘upon˜%’, ‘above˜’, ‘below˜%’, and ‘nextto˜’, one or more portions may be arranged between two other portionsunless ‘just’ or ‘direct’ is used.

In describing a time relationship, for example, when the temporal orderis described as ‘after˜’, ‘subsequent˜’, ‘next˜’, and ‘before˜%’, a casewhich is not continuous may be included unless ‘just’ or ‘direct’ isused.

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present disclosure.

“A first horizontal-axis direction”, “a second horizontal-axisdirection” and “a vertical-axis direction” should not be construed by ageometric relation only of a mutual vertical relation, and may havebroader directionality within the range that elements of the presentdisclosure may act functionally.

The term “at least one” should be understood as including any and allcombinations of one or more of the associated listed items. For example,the meaning of “at least one of a first item, a second item, and a thirditem” denotes the combination of all items proposed from two or more ofthe first item, the second item, and the third item as well as the firstitem, the second item, or the third item.

Features of various embodiments of the present disclosure may bepartially or overall coupled to or combined with each other, and may bevariously inter-operated with each other and driven technically as thoseskilled in the art can sufficiently understand. The embodiments of thepresent disclosure may be carried out independently from each other, ormay be carried out together in co-dependent relationship.

Hereinafter, the preferred embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.Wherever possible, the same reference numbers will be used throughoutthe drawings to refer to the same or like parts.

FIG. 1 is a plane view illustrating the state that a display apparatusaccording to one embodiment of the present disclosure is not bent, andFIG. 2 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the first embodiment ofthe present disclosure.

Referring to FIGS. 1 and 2, the display apparatus according to the firstembodiment of the present disclosure comprises a substrate 100, a pixelarray layer 120, a second substrate 140, and first and second coverlayers 150(1) and 150(2).

The first substrate 100 is a flexible substrate as a base substrate. Forexample, the first substrate 100 may include a transparent polyimidematerial. The first substrate 100 made of a polyimide material may be ahardened polyimide resin coated with a constant thickness on a frontsurface of a release layer provided on a carrier glass substrate. Thecarrier glass substrate is separated from the first substrate 100 byrelease of the release layer using a laser release process.

The substrate 100 includes a display area DA and a non-display area NA.

The display area DA is an area where an image is displayed, and may bedefined at a center portion of the first substrate 100. This displayarea DA may be defined as an area where the pixel array layer 120 fordisplaying an image is arranged.

The non-display area NA is an area where an image is not displayed, andmay be defined as an edge portion of the substrate 100 to surround thedisplay area DA.

A buffer layer 110 may be formed on the first substrate 100. The bufferlayer 110 is formed on an entire surface of the first substrate 100 toprevent water from being permeated into the display area DA through thefirst substrate 100. The buffer layer 110 according to one embodimentmay be made of a plurality of inorganic films which are depositedalternately. For example, the buffer layer 110 may be formed of amulti-layered film of one or more inorganic films of a silicon oxidefilm (SiOx), a silicon nitride film (SiNx), SiON and SiO₂, which aredeposited alternately. The buffer layer 110 may be omitted.

The pixel array layer 120 is arranged on the display area DA of thefirst substrate 100. That is, the pixel array layer 120 is provided onthe buffer layer 110 overlapped with the display area DA defined in thefirst substrate 100.

The pixel array layer 120 may include scan lines, data lines, drivingpower lines, a pixel driving circuit, and a light emitting diode layer.

The scan lines may be arranged in parallel with a first direction X ofthe first substrate 100 and spaced apart from each other along a seconddirection Y of the first substrate 100.

The data lines may be arranged in parallel with the second direction Yof the first substrate 100 and spaced apart from each other along thefirst direction X of the first substrate 100.

The driving power lines are arranged in parallel with the data lines.

The pixel driving circuit is provided in a pixel area defined bycrossing between the scan lines and the data lines and may include atleast two thin film transistors and at least one capacitor. The pixeldriving circuit emits the light emitting diode layer in accordance witha scan signal supplied from the scan line adjacent thereto, a drivingpower supplied from the driving power line adjacent thereto, and a datasignal supplied from the data line.

The light emitting diode layer emits light in accordance with the datasignal supplied from a pixel driving circuit of a corresponding pixel.The light emitted from the light emitting diode layer is emitted to theoutside by passing through the first substrate 100. The light emittingdiode layer may include a first electrode connected to the pixel drivingcircuit of the corresponding pixel, a light emitting layer formed on thefirst electrode, and a second electrode formed on the light emittinglayer.

The first electrode may be an anode electrode individually patterned inthe pixels. The first electrode is formed of a transparent metalmaterial such as ITO and IZO, which may transmit light.

The light emitting layer according to one embodiment may include a redlight emitting layer, a green light emitting layer and a blue lightemitting layer, each of which emits light corresponding to a color setto the pixel.

The light emitting layer according to another embodiment may be a commonlayer commonly formed in the pixels. In this case, a manufacturingprocess may be simplified. The light emitting layer may include any oneof an organic light emitting layer, an inorganic light emitting layer,and a quantum dot light emitting layer, or may include a deposited ormixed structure of an organic light emitting layer (or inorganic lightemitting layer) and a quantum dot light emitting layer. The lightemitting layer includes two or more light emitting portions for emittingwhite light. For example, the light emitting layer may include first andsecond light emitting portions for emitting white light by means ofmixture of the first light and the second light. In this case, the firstlight emitting portion emits the first light, and may include any one ofa blue light emitting portion, a green light emitting portion, a redlight emitting portion, a yellow light emitting portion, a yellow-greenlight emitting portion. The second light emitting portion may include alight emitting portion for emitting light having a complementary colorof the first light of the blue light emitting portion, the green lightemitting portion, the red light emitting portion, the yellow lightemitting portion, and the yellow-green light emitting portion.

The second electrode is a cathode electrode and may be a common layercommonly formed in the pixels. The second electrode may include a metalmaterial having high reflectivity. For example, the second electrode maybe formed of a multi-layered structure such as a deposition structure(Ti/Al/Ti) of Al and Ti, a deposition structure (ITO/Al/ITO) of Al andITO, an APC alloy (Ag/Pd/Cu), and a deposition structure (ITO/APC/ITO)of APC alloy and ITO, or may include a single layered structure of anyone material selected from Ag, Al, Mo, Au, Mg, Ca, and Ba, or an alloymaterial of two or more.

The second substrate 140 is arranged on the pixel array layer 120, andhas a first surface adjacent to the pixel array layer 120 and a secondsurface opposite to the first surface. The first surface of the secondsubstrate 140 is attached to the pixel array layer 120. The secondsubstrate 140 serves to primarily block oxygen or water from beingpermeated into the light emitting diode layer. The second substrate 140according to one embodiment may be a metal foil, a metal sheet, or ametal plate. For example, the second substrate 140 may be made of, butnot limited to, an alloy material of Fe and Ni, which has a low thermalexpansion coefficient.

The second substrate 140 includes a first area A1 and a second area A2bent from the first area.

The first area A1 is a plane area, and may be defined as an areaoverlapped with a front display area of the first substrate 100.

The second area A2 is a bending area, and may be defined as an areaoverlapped with an edge display area of the first substrate 100. Thesecond area A2 may be a portion which is bent in a curved type.

The second substrate 140 according to one embodiment may be formed tohave a respective thickness in the first area A1 and the second area A2.For example, the second substrate 140 in the first area A1 may be formedto have a thickness thicker than that in the second area A2. The secondsubstrate 140 may be formed through a partial etching process of thesecond area A2. For example, the second area A2 may partially be etchedusing processes including an etching process and a laser process.

Since the second substrate 140 is formed to have a respective thicknessin the first area A1 and the second area A2, a step difference is formedin a boundary between the first area A1 and the second area A2. Forexample, the step difference may have a range of 40 μm to 60 μm.

The display apparatus according to the present disclosure may facilitatebending because the second substrate 140 is formed at differentthicknesses. If a thickness of a bending area of the display apparatusis reduced, stress generated during bending is reduced, and homeostasisof the display panel may be maintained. In this way, if the first areaA1 is formed to have a thickness thicker than that of the second area A2in the second substrate 140, stress applied to the display panel may bereduced, and a wide choice of a curvature radius may be obtained,whereby a bezel size of the display panel may be reduced.

The first surface of the second substrate 140 is attached to the pixelarray layer 120 by an adhesive layer 130. The adhesive layer 130 may bea thermal hardening adhesive or a natural hardening adhesive. Forexample, the adhesive layer 130 may be made of a material such as adecompression adhesive or a barrier decompression adhesive having amoisture absorption function.

The first and second cover layers 150(1) and 150(2) are provided on thenon-display area NA of the first substrate 100 to adjoin the side of thesecond substrate 140. The first and second cover layers 150(1) and150(2) may be made of urethane or acryl, which include a polymermaterial. The cover layer 150 according to one embodiment may beprovided to be higher than the adhesive layer 130 in the non-displayarea NA adjacent to the display area DA of the firs substrate 100,thereby preventing water permeation through the adhesive layer 130.

The first and second cover layers 150(1) and 150(2) according to oneembodiment is provided to prevent rolling of the first substrate 100during a process of separating a carrier glass substrate from the firstsubstrate 100 by release of a release layer using a laser releaseprocess. In detail, since the second substrate 140 is not provided inthe non-display area NA of the first substrate 100, the first substrate100 which is flexible and thin is rolled. The first and second coverlayers 150(1) and 150(2) may be provided on the non-display area NA ofthe first substrate 100 to prevent rolling of the first substrate 100from occurring, and then to facilitate a lamination process of forming alight-transmittance layer 160 for supporting the first substrate 100.

Additionally, the display apparatus according to the present disclosurefurther comprises a display driving circuit portion 200.

The display driving circuit portion 200 is connected to a pad portionprovided on the non-display area NA of the first substrate 100 todisplay an image corresponding to image data supplied from a displaydriving system on each pixel. The display driving circuit portion 200according to one embodiment includes a plurality of flexible circuitfilms 210, a plurality of data driving integrated circuits 220, aprinted circuit board 230, and a timing controller 240.

Input terminals provided at one side of each of the plurality offlexible circuit films 210 are attached to the printed circuit board 230by a film attachment process, and output terminals provided at the otherside of each of the plurality of flexible circuit films 210 are attachedto the pad portion provided on the first substrate 100 by a filmattachment process.

Each of the plurality of data driving integrated circuits 220 ispackaged in each of the plurality of flexible circuit films 210. Each ofthe plurality of data driving integrated circuits 220 receives pixeldata and data control signal supplied form the timing controller 240,and converts the pixel data to analog type pixel data in accordance withthe data control signal and then supplies the converted data to the dataline.

The printed circuit board 230 serves to support the timing controller220 and transfer signals and power sources between elements of thedisplay driving circuit portion 200.

The timing controller 240 is packaged in the printed circuit board 230,and receives the image data and timing synchronization signal suppliedform the display driving system through a user connector provided in theprinted circuit board 230. The timing controller 240 generates pixeldata by aligning the image data to be matched with a pixel arrangementstructure of the pixel array layer 120 on the basis of the timingsynchronization signal, and provides the generated pixel data to thecorresponding data driving integrated circuit 220. Also, the timingcontroller 240 generates each of a data control signal and a scancontrol signal on the basis of the timing synchronization signal,controls a driving timing of each of the plurality of data drivingintegrated circuits 220 through the data control signal, and controls adriving timing of a scan driving circuit through the scan controlsignal. In this case, the scan control signal may be supplied to thecorresponding scan driving circuit through the first and/or lastflexible circuit films of the plurality of flexible circuit films 210.

Additionally, the display apparatus according to the present disclosurefurther comprises a light transmittance layer 160 attached to the firstsubstrate 100 to overlap the first substrate 100.

The light transmittance layer 160 is attached to the second surfaceopposite to the first surface provided with the buffer layer 110 formedon the first substrate 100, by a transparent adhesive layer. The lighttransmittance layer 160 according to one embodiment may be made of aflexible film, for example, at least one of a polyethylene terephthalatefilm, anti-reflection film, a polarizing film and a transmittancecontrollable film. The light transmittance layer 160 may be attached tothe second surface of the first substrate 100 separated from the carrierglass substrate. The transparent adhesive layer may be an opticallyclear resin (OCR) or an optically clear adhesive (OCA).

FIG. 3 is a cross-sectional view illustrating a bent state of a displayapparatus shown in FIG. 2.

Referring to FIG. 3, the display apparatus 100 according to the presentdisclosure is bent to have a curved type. That is, an edge display areaof the first substrate 100 is bent toward the second surface of thesecond surface 140 to have a certain curvature radius and thus surroundsthe side of the second substrate 140. At this time, the edge displayarea of the first substrate 100 may be bent to have a curvature radiusof 1 mm to 5 mms.

An edge display screen (or sub display screen) is provided at the edgeof the display area DA bent in a curved type as above. On the otherhand, a front display screen (or main display screen) whichsubstantially has a plane state is provided in the display area DA whichis not bent.

As described above, the display apparatus according to the presentdisclosure may facilitate bending because the second area A2 of thesecond substrate 140 is formed to be thinner than the first area A1.Also, a bezel width of 10 μm or less may be obtained in accordance withbending, and damage of the thin film transistor and/or the lightemitting diode layer may be avoided during bending.

FIG. 4 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the second embodiment ofthe present disclosure, and FIG. 5 is a cross-sectional view taken alongline I-I′ of FIG. 1, illustrating a display apparatus according to thethird embodiment of the present disclosure.

Referring to FIGS. 4 and 5, the display apparatus according to thesecond and third embodiments of the present disclosure comprises a firstsubstrate 100, a pixel array layer 120, a second substrate 140, a coverlayer 150, and a passivation layer 170. Repeated description of theaforementioned description will be omitted, and the passivation layer170 will be described.

The passivation layer 170 is provided on the second area A2 of thesecond substrate 140. The passivation layer 170 is formed to cover thesecond area A2 of the second substrate 140, thereby preventing thesecond substrate 140 from being oxidized. The passivation layer 150 maybe formed by, but not limited to, atmospheric pressure plasma processand low temperature deposition process.

The second area A2 of the second substrate 140 according to oneembodiment is the area partially etched by an etching process, and maybe exposed to external water and oxygen. Since the second substrate 140is made of a metal material, it may be vulnerable to corrosion, and ifthe surface of the second substrate 140 is removed by an etchingprocess, the second substrate is easily exposed to external water andoxygen, whereby oxidization (rust) is generated. If oxidization (rust)is generated in the second substrate 140, a thickness of the surface ischanged, and a rough surface may be generated by step difference causedby the thickness change.

The passivation layer 170 according to one embodiment may be provided onthe second area A2 of the second substrate 140 to prevent oxidization ofthe etched portion. The passivation layer 170 may prevent corrosion ofthe second substrate 140 from occurring by blocking oxygen and/or waterfrom being permeated into the second substrate 140. The passivationlayer 170 may be made of a single layer or multiple layers. For example,the passivation layer 170 may be formed of any one of SiOx, SiNx, andSiON, or may be formed of multiple layers of one or more inorganic filmsdeposited alternately.

The passivation layer 170 may be formed to have a thin thickness of 1 μmor less. Since the second area A2 of the second substrate 140corresponds to the area of which thickness is reduced to facilitatebending, the passivation layer 170 is formed at a thin thickness tomaintain the thin thickness of the second area. For example, since thesecond substrate 140 in the second area A2 may be formed at a thicknessof 20 μm to 80 μm, the passivation layer 170 is formed at a thicknessthinner than the second substrate 140. Therefore, the thickness of thesecond substrate 140 in the second area A2 and the thickness of thepassivation layer 170 are thinner than the thickness of the secondsubstrate 140 in the first area A1. In this way, since the passivationlayer 170 is formed at a thin thickness, stress applied to the displaypanel may not be increased and at the same time oxidization of thesecond substrate 140 may be avoided.

Referring to FIG. 5 again, the passivation layer 170 according to oneembodiment may be provided to cover the boundary between the first areaA1 and the second area A2.

If the second substrate 140 is partially etched by an etching process,oxidization of the second substrate 140 may be generated even at theboundary portion between the first area A1 and the second area A2 aswell as the second are A2. The passivation layer 170 may be formed atsome area of the end of the first area A1 constituting the boundary withthe second area A2 to fully cover the boundary portion between the firstarea A1 and the second area A2. In this way, the passivation layer 170may be formed to fully cover the boundary portion between the first areaA1 and the second area A2 to prevent oxidization from occurring at somearea of the end of the first area A1 as well as the second area A2.

FIG. 6 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the fourth embodiment ofthe present disclosure, FIG. 7 is a cross-sectional view taken alongline I-I′ of FIG. 1, illustrating a display apparatus according to thefifth embodiment of the present disclosure, and FIG. 8 is across-sectional view taken along line I-I′ of FIG. 1, illustrating adisplay apparatus according to the sixth embodiment of the presentdisclosure.

Referring to FIGS. 6 to 8, the display apparatus according to the fourthto sixth embodiments of the present disclosure comprises a firstsubstrate 100, a pixel array layer 120, a second substrate 140, a coverlayer 150, a passivation layer 170, and a groove 180. Repeateddescription of the aforementioned description will be omitted, and thegroove 180 will be described.

The groove 180 is provided in the second area A2 of the second substrate140. The groove 180 is provided between the boundary of the first areaA1 and the second area A2 and an end portion DP of the second substrate140. The end portion DP may be defined at both ends of the secondsubstrate 140, and may be a portion included in the second area A2.

The display apparatus according to one embodiment is provided in astructure that the second substrate 140 is not fully etched in thesecond area A2 and has the groove 180. Since the second area A2corresponds to the area located at both ends of the second substrate140, the side of the second substrate 140 may be etched together withthe second substrate 140 during the process of etching the secondsubstrate 140 in the second area A2. However, the display apparatusaccording to the present disclosure may be provided in a structure thatthe second substrate 140 of the other area except the end portion DP inthe second area A2 is etched to form the groove 180.

In the display apparatus according to one embodiment, since the secondsubstrate 140 of the end portion DP is not etched, the problem that theside of the second substrate 140 is etched may be solved. The endportion DP has a width smaller than that of the second area A2, andcorresponds to the portion less affected by a stress than the centerportion of the second area A2 during bending. Therefore, even though thesecond substrate 140 of the end portion DP is not etched, if the secondsubstrate 140 in the second area A2 other than the end portion DP isetched, a stress generated during bending may be reduced.

The display apparatus according to one embodiment may further comprisethe passivation layer 170 for covering the groove 180. In this case, thepassivation layer 170 may be provided inside the groove 180, and may beprovided to cover the boundary of the first area A1 and the second areaA2 and the end portion DP. Since the passivation layer 170 has the samefeatures as those of the aforementioned passivation layer, its repeateddescription will be omitted.

FIG. 9 is a cross-sectional view taken along line I-I′ of FIG. 1,illustrating a display apparatus according to the seventh embodiment ofthe present disclosure.

Referring to FIG. 9, the display apparatus according to the seventhembodiment of the present disclosure comprises a first substrate 100, apixel array layer 120, a second substrate 140, a cover layer 150, apassivation layer 170, and a groove 180. Repeated description of theaforementioned description will be omitted, and description will begiven based on a difference from the aforementioned embodiments.

The passivation layer 170 is provided to cover an entire surface of thesecond substrate 140. Since the second substrate 140 is made of a metalmaterial, oxidization may be generated even in case of the portion whichis not etched. In the display apparatus according to the presentdisclosure, since the passivation layer 170 is formed to cover theentire surface of the second substrate 140, oxidization, which may occurin the area that is not etched as well as the area that is partiallyetched, may be avoided. In this way, if the passivation layer 170 isprovided on the entire surface of the second substrate 140, oxidizationin all areas of the second substrate 140 may be avoided, wherebyreliability may be obtained.

As described above, the display apparatus according to the presentdisclosure has advantages in that it is optimized for a stress tofacilitate bending of the bending portion and the pixel array layerprovided on the bending portion may be prevented from being damagedduring bending.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present disclosurewithout departing from the spirit or scope of the disclosures. Thus, itis intended that the present disclosure covers the modifications andvariations of this disclosure provided they come within the scope of theappended claims and their equivalents. Thus, the above embodiments areto be considered in all respects as illustrative and not restrictive.The scope of the disclosure should be determined by reasonableinterpretation of the appended claims and all change which comes withinthe equivalent scope of the disclosure are included in the scope of thedisclosure.

What is claimed is:
 1. A display apparatus comprising: a first substratehaving a display area and a non-display area; a pixel array layerprovided on the display area of the first substrate; and a secondsubstrate provided on the pixel array layer, having a first area and asecond area, the first area and the second area disposed within aboundary of the pixel array layer, wherein a second area thickness isthinner than a first area thickness, and wherein portions of the firstsubstrate and the pixel array corresponding to the second area of thesecond substrate are bent with the second area.
 2. The display apparatusof claim 1, further comprising a passivation layer provided on thesecond area of the second substrate.
 3. The display apparatus of claim2, wherein the first area thickness is thicker than a sum of the secondarea thickness and a passivation layer thickness.
 4. The displayapparatus of claim 2, wherein the passivation layer thickness is thinnerthan the second area thickness.
 5. The display apparatus of claim 2,wherein the passivation layer covers a boundary between the first areaand the second area of the second substrate.
 6. The display apparatus ofclaim 2, wherein the passivation layer is formed of a single layer ormultiple layers of SiNx and SiOx.
 7. The display apparatus of claim 1,wherein the second substrate is a metal foil, a metal sheet, or a metalplate.
 8. The display apparatus of claim 1, wherein the second substrateincludes a step difference formed in a boundary between the first areaand the second area, wherein the step difference has a range of 40 μm to60 μm.
 9. The display apparatus of claim 1, wherein the second substrateis attached to the pixel array layer by an adhesive layer.
 10. Thedisplay apparatus of claim 9, wherein the adhesive layer includes adecompression adhesive or a barrier decompression adhesive having amoisture absorption function.
 11. A display apparatus comprising: a baselayer; a first cover layer covering a first end and a second cover layercovering a second end of the base layer; a pixel array layer on top ofthe base layer, the pixel array layer extending between the first coverlayer and the second cover layer; a first substrate on top of the pixelarray layer and within a boundary of the pixel array layer, the firstsubstrate having a first portion adjacent to the first cover layer, asecond portion connecting the first and a third portion, and the thirdportion adjacent to the second cover layer, the first and the thirdportions of the first substrate having a first thickness and the secondportion having a second thickness; and a second substrate on a bottom ofthe pixel array layer, wherein the first thickness is different than thesecond thickness.
 12. The display apparatus of claim 11, wherein thefirst thickness is thinner than the second thickness.
 13. The displayapparatus of claim 11, further comprising: the base layer having a firstend portion and a second end portion, the first end portion having acurvature radius that includes the first portion of the first substrateand the second end portion having the curvature radius that includes thethird portion of the first substrate.
 14. The display apparatus of claim13, wherein the curvature radius has a range of 1 mm to 5 mm.
 15. Thedisplay apparatus of claim 13, further comprising: the second portion ofthe first substrate having no curvature radius.
 16. The displayapparatus of claim 11, further comprising: a vertical offset between thefirst portion and the second portion and a second vertical offsetbetween the third portion and the second portion.
 17. The displayapparatus of claim 16, further comprising: a first passivation layercovering the vertical offset; and a second passivation layer coveringthe second vertical offset.
 18. The display apparatus of claim 11,further comprising: a first passivation layer covering the first portionof the first substrate; and a second passivation layer covering thethird portion of the first substrate.